Cold hardiness & minimum temperature

Is Common Broomrape (Orobanche minor)cold hardy? Hardiness zone & min temp

Also called Common Broomrape, Hellroot, Clover Broomrape, Lesser Broomrape.

More about common broomrape

About Common Broomrape

Orobanche minor · also called Common Broomrape, Hellroot · flowering

Orobanche minor is a holoparasitic annual to short-lived perennial wildflower native to the UK and temperate Europe, attaching to the roots of host plants — chiefly clovers (Trifolium spp.) and other Fabaceae and Asteraceae — from which it extracts all water and nutrients. It lacks chlorophyll and cannot photosynthesize; it is entirely dependent on its host and will not grow without one. Stems range from yellow-brown to reddish-purple and bear creamy-white to lilac tubular flowers from May to August. It is the most widespread British broomrape, common in the south of England on disturbed ground, roadsides, and chalk grassland. Toxicity to cats and dogs is not established; classified as mildly-toxic out of caution.

Cold limit: USDA 6-9 · RHS H5 (-10 to 28°C)

What common broomrape's hardiness rating actually means

Yes — common broomrape is genuinely cold hardy. Rated RHS H5 and USDA 6-9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H5 means: Hardy in most of the UK and in cold winters. On the US scale that maps to USDA 6-9 — the zones where it can be left outdoors year-round.

New to these scales? The USDA hardiness zone map explained covers how the zone numbers work, and you can find your own zone with the zone finder.

Minimum temperature — and what happens below it

Minimum survivable temperature is roughly about −15 to −10 °C. Common Broomrape is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for common broomrape as it gets too cold:

It tolerates winter lows to about −15 to −10 °C once established.
Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root.
First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.

Can common broomrape go outside or overwinter — and where?

Plant it out within USDA 6-9 and it overwinters with little or no help.
It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy.
The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

Work back from your local frost dates with the frost-date calculator: the last spring frost and first autumn frost are what really decide when common broomrape can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Common Broomrape hardiness — frequently asked questions

Is common broomrape cold hardy?

Yes — common broomrape is genuinely cold hardy. Rated RHS H5 and USDA 6-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Common Broomrape is hardy across USDA 6-9; it belongs in the ground or a frost-proof container, not on a windowsill, and many types actively need a cold winter to perform.

What is the minimum temperature common broomrape can survive?

Minimum survivable temperature is roughly about −15 to −10 °C. Common Broomrape is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is common broomrape?

Common Broomrape is rated USDA 6-9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can common broomrape survive winter outside?

Plant it out within USDA 6-9 and it overwinters with little or no help. It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy. The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

What happens to common broomrape below its minimum temperature?

It tolerates winter lows to about −15 to −10 °C once established. Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root. First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.